Why are stones layed in switch yard?
Gravel/Stones in the Substation Switchyard are provided to reduce the step potential and touch potential when operators work on Switchyard. Step Potential – It is the potential developed between the two feet on the ground of a man when a short circuit occurs. In addition to this, the main reasons are based on:
First of all, we use stone in our electrical substation for reducing the Ground Potential Rise (GPR) and in electrical engineering, it is also called Earth Potential Rise (EPR) and it occurs when a large current flows to earth through the earth grid impedance.
Stone increase the resistance of soil, for this reason, step potential, and the touch potential limit decrease. When people are working in substations stone reduces the possibility of electric shock during work.
Below is our transformer oil filtration machine at the site, and you could see that it is also located on gravel, now you know the reason already.